Drum

Background

A drum is a musical instrument which produces sound by the vibration of a
stretched membrane. The membrane, which is known as the head, covers one
or both ends of a hollow body known as the shell. Instruments that produce
sound by means of a vibrating membrane are also known as membranophones.
Drums are part of the larger category of musical devices known as
percussion instruments. Percussion instruments other than membranophones
are known as idiophones. Idiophones, such as bells and cymbals, produce
sound by the vibration of the instrument itself rather than by an attached
membrane.

Drums exist in a wide variety of shapes and sizes. The two basic shapes
for shells are bowls and tubes. The most familiar bowlshaped drums in
Western music are kettledrums, also known as timpani. Tubular drums may be
taller than they are wide, such as conga drums, or shorter than they are
wide. Short drums, also known as shallow drums, are the most common
tubular drums used in Western music. Shallow drums include snare drums,
tenor drums, and bass drums. If a tubular drum is so shallow that the
shell does not resonate, it is known as a frame drum. The most familiar
type of frame drum is the tambourine.

Drums are usually played by being struck. Some drums, such as bongo drums,
are designed to be played by striking them directly with the hand. In
modern Western music, most drums are designed to be played by being struck
with various devices known as beaters. The most familiar beaters are
wooden sticks, generally used to play smaller drums such as snare drums,
and padded wooden mallets, used to play larger drums such as bass drums.
Sometimes drums are struck with wire brushes or other types of beaters to
produce a different sound.

Some drums, particularly in non-Western cultures, are played in ways other
than being struck. Rattle drums contain pellets within the shell or
knotted cords attached to the head and are played by being shaken.
Friction drums are played by being rubbed. Some membranophones have the
vibrating membrane set into motion by sound waves coming from a human
voice or from another musical instrument. These devices are known as
mirlitons. The most familiar mirliton is the kazoo.

Drums are either tunable, so that they produce a particular note, or
nontunable. Most drums in Western music are nontunable. The only commonly
used tunable drums in Western music are timpani. Idiophones, which exist
in an even greater variety than membranophones, may also be tunable, such
as a xylophone, or nontunable, such as a rattle.

History

Percussion instruments have been used since prehistoric times. The
earliest drums consisted of fish or reptile skin stretched over hollow
tree trunks and were struck with the hands. Somewhat later the skins of
wild or domesticated mammals were used to make larger drums which were
struck with sticks. Besides tree trunks, skins were also stretched over
pits dug into the ground to make large drums or over openings in pots or
gourds to make small drums.

Frame drums were used by the ancient civilizations of the Middle East
about 5,000
years ago. They were later adapted by the ancient Greeks and Romans. The
Romans also used tubular drums with skins stretched over both ends of a
hollow shell. After the fall of Rome, drums were not commonly used in
Western Europe, although they continued to be used by the Arabs. The
Crusades brought Europeans in contact with the Arab culture. From the
Arabs, Europeans adapted the tambourine (a small frame drum), the naker (a
small kettledrum), and the tabor (a small tubular drum). The tabor was
often used with a snare, which consisted of thin cords of animal gut
stretched across one of the heads in order to produce a rattling sound.
The snared tabor is the ancestor of the modern snare drum.

Large kettledrums, long used in the Middle East, were introduced to
Western Europe in the fifteenth century. These instruments consisted of
calfskin stretched over large copper cauldrons and were used for military
and ceremonial purposes. They were first used in orchestras in the late
seventeenth century.

The bass drum, a large tubular drum, was rare in Europe until the late
eighteenth century. The snare drum and the tenor drum (a somewhat larger
version of the snare drum, but without the snare) were used primarily for
military purposes until the nineteenth century.

Timpani became an important part of orchestral music during the nineteenth
century. During the 1880s, devices were developed which allowed timpani
players to change the pitch of the instrument quickly, allowing them to
play more complex melodies.

An important development in drum manufacturing occurred in the 1950s when
drum makers began to experiment with using plastic instead of animal skin
to make heads. Although some drummers, particularly timpani players,
preferred the sound of heads made with animal skins, plastic heads soon
almost completely replaced traditional heads. A few individual drum makers
still make heads from animal skins for musicians who prefer this type of
product.

During the twentieth century, percussion instruments of all kinds became
important in both orchestral music and in popular music. A modern drum set
used by popular musicians such as jazz and rock drummers often consists of
a bass drum struck with a mallet operated by a foot pedal, a snare drum, a
series of tubular drums of various sizes, and a set of cymbals.

Raw Materials

Until the late 1950s, the head of a drum was almost always made of animal
skin. Modern heads are now almost always made of plastic. Usually some
form of polyester is used. Polyesters are plastics in which numerous small
molecules are linked together into a long chain using a chemical bond
known as an ester group. The most common form of polyester used in the
drum industry is known as polyethylene terephthalate, available under
trade names such as Mylar. Polyethylene terephthalate has the advantage of
being strong and resistant to moisture, heat, sunlight, and many
chemicals. Polyethylene terephthalate is made from the chemical compounds
ethylene glycol and terephthalic acid. These substances are derived from
petroleum

The shell of a drum is usually made of wood. Commonly used woods include
maple, birch, and poplar. Some drums have a shell made of metal. Commonly
used metals include steel, aluminum, brass, and bronze. Sometimes
synthetic materials are used to make shells. These materials are usually
strong, hard plastics.

The various hardware components that hold the drum together are usually
made of steel. Sometimes other metals such as brass or aluminum are used.
In some cases, these components are made of wood or strong plastic.

Optional attachments such as stands to hold the drum in front of the
drummer are usually made of steel or aluminum. Straps to hold the drum in
place while marching in a band are generally made from leather, plastic,
or cloth. The snare of a snare drum consists of thin strands of various
materials such as steel, aluminum, plastic, or animal gut.

The Manufacturing
Process

Making the hardware components

1 Metal hardware components are made using precision metalworking
equipment

Drum head material is made by cooling hot liquid plastic on a large
metal roller to form a solid, then stretched between smaller metal
rollers to produce a thin film.

such as drills and lathes. Wood hardware components are carved from
blocks of wood using various kinds of cutting instruments. Plastic
hardware components are often made using a process known as injection
molding. This process involves heating the plastic until it melts,
injecting the molten plastic into a mold in the shape of the desired
component, allowing the plastic to cool back into a solid, opening the
mold, and removing the completed component.

Making the head

2 Polyethylene terephthalate is made by combining terephthalic acid (or
a derivative such as dimethyl terephthalate) with ethylene glycol. These
chemicals are subjected to heat to produce hot, liquid plastic. The
liquid is cooled on a large metal roller to form a solid, then stretched
between smaller metal rollers to produce a thin film. Various additives
may be included to produce films in many colors, which may be either
transparent or opaque.

3 The polyethylene terephthalate film is shipped to the drum
manufacturer on large rolls. Circles of the proper sizes to make drum
heads are cut from the film using precision cutting tools.

4 The edge of the plastic circle is softened by a heating element and
allowed to cool to form a collar around the circumference. A steel ring
is placed within the collar and an aluminum ring is placed outside the
collar. The ring is then closed on a rolling machine to produce a
tubular, secure circle of metal, which serves to keep the plastic skin
taut. The completed head is stored until needed for assembly.

Making the shell

5 Metal shells are made using a variety of methods including casting
(pouring molten metal into a mold in the shape of the shell) and
machining (shaping the metal with various metalworking machines such as
drills and lathes). Plastic shells may be made using injection molding.

6 Most shells are made of wood. Wooden shells are made from large, thin
panels of wood known as veneer. Veneer is cut from lumber with large
saws and shipped from the lumber company to the drum manufacturer.

7 Veneer is cut to the proper size to make the shell by a
computer-controlled saw. The cut pieces of veneer are sorted by size and
stored under controlled temperature and humidity until needed.

8 Pieces of cut veneer of the proper sizes are moved through a glue
press. This device applies glue to the veneer as it passes

Schematic diagram of the formation of the plastic drum heads.

between large metal rollers. The pieces of veneer are then rolled
together to form a cylinder consisting of about 7-9 layers of veneer.
The rolled veneer is inserted into a metal mold of the proper size to
make the desired shell.

9 A variety of methods exist to apply pressure to the glued layers of
veneer within the mold. A bag within the mold may be inflated to apply
pressure. Water or oil may also be used to apply pressure. The glue may
be allowed to dry slowly on its own or an electrical current may be
applied to dry the glue quickly.

10 The shell is removed from the mold. It is then cut with a rapidly
rotating blade to produce a 45° angle on its edge. In other words,
the layers of veneer are cut at slightly different heights, with the
innermost layer being the shortest and the outermost layer being the
tallest. This sloping edge will allow the head to fit in place.

11 The shell is sanded with high power sanders to produce a smooth
surface. It is then either stained or covered with a sheet of shiny,
decorative plastic in various colors and patterns. If it is stained, it
is rotated while wood stain of various colors is sprayed on it. The
stain is then dried quickly with ultraviolet light. A clear, shiny
topcoat is then applied and dried in a similar way.

Assembling the drum

12 Precision drills are used to drill holes in the shell to allow the
hardware components to be attached. Lugs, which hold the head in place,
are screwed into the shell. Long, thin metal rods known as tension rods
pass through the aluminum ring surrounding the head and into the lugs.
The degree of tension on the head can be controlled by using a drum key,
which tightens or loosens the tension rods.

13 For a snare drum, a small amount of one edge of the shell is cut away
to allow the snare to fit in place so that it touches one of the heads.
The snare is attached in such a way that it can either be held tight,
producing the snared sound, or held loose, producing the unsnared sound.

Packaging and shipping

14 The drum is placed in a plastic bag. It is then placed in a cardboard
box containing pieces of expanded polystyrene foam, a firm, light
plastic that prevents the drum from moving during shipping. The boxes
are then shipped to musicians, music
stores, orchestras, marching bands, and other consumers.

Quality Control

The most important factor in the quality control of drum manufacturing is
the size and shape of the various components. The wooden veneer must be
cut to the precise size to allow several layers to fit together to form a
cylinder. The plastic head and the metal rings that hold it in place must
fit together properly. The lugs and other hard-ware components must be
positioned correctly in exact holes drilled in the proper places in the
shell.

The external appearance of the drum is important to drummers. Each drum is
visually inspected to ensure that the wood stain or decorative plastic
wrapping is free from defects.

The Future

During the 1980s, it seemed that electronic drum machines (flat panels
that produce a synthesized sound when struck) might replace traditional
drums in popular music. It soon became obvious that drummers preferred
playing traditional drums. In the future, small electronic devices may be
attached to drums to allow the sound to be manipulated in new ways while
allowing the drummer to enjoy the experience of playing traditional drums.